Why can certain animals regenerate limbs but humans cannot?

Throughout evolution, certain animals have developed the ability to regenerate their limbs. This is mainly do to their size, genetic makeup, and their place on the food chain. Animals that are predators yet get preyed on by bigger animals tend to have this ability. The reason why humans don't have this is because we on the top of the food chain and we have the mental prowess to develop medicine to keep us living longer.

They evolved this way. Humans have never really needed to regenerate limbs, therefore we didn't evolve to. However, with our ever growing technology, we have limb replacements. They aren't as well functioning as a regenerated limb, however we are getting closer by the minute.